From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp1 ([2001:41d0:8:6d80::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by ms11 with LMTPS id iLlTM7IzT2C9LQAA0tVLHw (envelope-from ) for ; Mon, 15 Mar 2021 10:15:14 +0000 Received: from aspmx1.migadu.com ([2001:41d0:8:6d80::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp1 with LMTPS id KKoIL7IzT2D1HgAAbx9fmQ (envelope-from ) for ; Mon, 15 Mar 2021 10:15:14 +0000 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by aspmx1.migadu.com (Postfix) with ESMTPS id A69382FF84 for ; Mon, 15 Mar 2021 11:15:13 +0100 (CET) Received: from localhost ([::1]:46376 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lLkFk-0003nm-0H for larch@yhetil.org; Mon, 15 Mar 2021 06:15:12 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49334) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lLkFa-0003nN-Ae for bug-guix@gnu.org; Mon, 15 Mar 2021 06:15:03 -0400 Received: from debbugs.gnu.org ([209.51.188.43]:51604) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lLkFa-0001YL-2V for bug-guix@gnu.org; Mon, 15 Mar 2021 06:15:02 -0400 Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1lLkFZ-000839-Ti for bug-guix@gnu.org; Mon, 15 Mar 2021 06:15:01 -0400 X-Loop: help-debbugs@gnu.org Subject: bug#46942: ci.guix.gnu.org is slow from my system Resent-From: raid5atemyhomework Original-Sender: "Debbugs-submit" Resent-CC: bug-guix@gnu.org Resent-Date: Mon, 15 Mar 2021 10:15:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 46942 X-GNU-PR-Package: guix X-GNU-PR-Keywords: To: Maxime Devos Cc: "pengmeiyu@riseup.net" , "46942@debbugs.gnu.org" <46942@debbugs.gnu.org>, zimoun Received: via spool by 46942-submit@debbugs.gnu.org id=B46942.161580328930908 (code B ref 46942); Mon, 15 Mar 2021 10:15:01 +0000 Received: (at 46942) by debbugs.gnu.org; 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charset=utf-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-guix@gnu.org List-Id: Bug reports for GNU Guix List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-guix-bounces+larch=yhetil.org@gnu.org Sender: "bug-Guix" Reply-to: raid5atemyhomework X-ACL-Warn: , raid5atemyhomework From: raid5atemyhomework via Bug reports for GNU Guix X-Migadu-Flow: FLOW_IN ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1615803313; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding:resent-cc: resent-from:resent-sender:resent-message-id:in-reply-to:in-reply-to: references:references:list-id:list-help:list-unsubscribe: list-subscribe:list-post:dkim-signature; bh=BOJBcJTwkqGHRJ02CSvLjeio6qW1WGYiVB8Awdi5jSQ=; 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dkim=fail ("headers rsa verify failed") header.d=protonmail.com header.s=protonmail header.b=h4NBirE0; dmarc=pass (policy=none) header.from=gnu.org; spf=pass (aspmx1.migadu.com: domain of bug-guix-bounces@gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=bug-guix-bounces@gnu.org X-Migadu-Queue-Id: A69382FF84 X-Spam-Score: -1.40 X-Migadu-Scanner: scn0.migadu.com X-TUID: FK+JSA9ypSOq > Hi Maxime, > > > On Mon, 2021-03-15 at 00:13 +0000, raid5atemyhomework via Bug reports f= or GNU Guix wrote: > > > > > Hello all, > > > [...] > > > I recently had to rebuild an OS (because I was dumb; the Guix languag= e > > > for shepherd services can easily lead you deadlocking shepherd itself= ) > > > and had supreme difficulty reinstalling, [...] > > > > Reinstalling after a messed up configuration file shouldn't be necessar= y. > > At least when using GRUB as bootloader, guix keeps some old (& presumab= ly > > not broken) system generations around, that can be selected when bootin= g > > from the bootloader. (I don't recall exactly how the menu is named, > > maybe =E2=80=98Old system generations of $HOSTNAMES?) > > Unfortunately I had a long-standing latent bug in my configuration file t= hat triggered on a (persistent on-disk) edge case which would cause the she= pherd process to enter an infinite loop (because the shepherd configuration= language is Turing-complete enough to allow infinite loops in the first pl= ace). All the remaining generations (since I didn't like keeping more than = a dozen, and had recently been excessively tweaking the configuration file)= had this bug, so I had no way of reverting to an even older generation tha= t predated the bug. And regardless, this kind of problem shouldn't occur in the first place. * Instead of running the `start` code in the same process 1 (which is speci= al enough that no amount of `kill -s SIGKILL 1` will work even if you manag= e to log into a console), `shepherd` should really run it in a separate pro= cess and monitor it if it's taking too long and possibly allow the operator= to break out of it. Principle of least power and all that... * If you want details: there is a shepherd service A that is a requiremen= t of shepherd service B, however the daemon launched by A needed to reach a= particular point in its initialization before B can start talking to it. = B itself will fail to start if A has not reached that point in initializati= on. The extra code I added to the `start` of shepherd service A was to wai= t for that point of initialization before A was considered "started". It t= urned out it was buggy in that if the point was not reached in 1 second it = would inadvertently enter an incorrect looping logic (ironically, the logic= was supposed to exit it after 60 seconds, but I got increment/decrement cr= ossed, meaning it would always loop as long as you never reached -60 second= s, which was impossible....) that ended up being an infinite loop and preve= nting process 1 from advancing. And this point was getting delayed when th= e process launched by A had to do a lot of (important) data on-disk that it= needed to process at startup, so it was persistent on-disk data that would= need > 1 second to process, thus ensuring that the buggy code would be ent= ered. * If this was a new computer it would also be just as screwed during instal= lation anyway, you should consider this a fortuitous discovery of a latent = bug. * New users trying out Guix System that happen to get hit by this bug mig= ht very well decide that Guix is not stable enough for them to commit to us= ing. Thanks raid5atemyhomework